1. Field of the Invention
The present invention relates to a system used to operate a multi-disk cartridge with a disk drive. More particularly, the invention concerns a method and apparatus for ensuring the proper position and orientation of a multi-disk cartridge, and for selectively locking the cartridge while it is inserted in the disk drive to prevent withdrawal of the cartridge while the disk drive is conveying one of the cartridge's disks.
2. Description of the Related Art
Today's market offers a variety of media for storing digital data. Many of these involve disk-shaped storage devices such as rigid 3.5" diskettes, floppy 5.25" diskettes, and single-disk optical cartridges, all of which enjoy widespread use with personal computers. Presently, these storage schemes do not require or provide any means for locking the storage device in the disk drive.
With rigid diskette drives, for instance, the diskette is inserted completely into the drive to use it, whereupon the diskette is inaccessible by human users. To eject the diskette, the user simply presses a button typically positioned on the drive's face. Pressing the button mechanically ejects the rigid diskette from the drive.
With floppy diskette drives, the diskette is also inserted completely into the drive. When fully inserted, however, the drive exposes a small gripable portion of the diskette. After the diskette is inserted into the drive, the drive will not access the diskette until the user manually pivots a latch to block withdrawal of the diskette. To remove the diskette, the user simply pivots the latch into its dormant position, and slidably removes the diskette from the drive.
Known optical data storage disks are provided in single disk packages called "cartridges". These cartridges are designed to be operated like rigid diskettes. Namely, a single-disk optical cartridge is inserted completely into a corresponding drive, making the cartridge inaccessible by human users. To remove the cartridge, the user presses an unload button positioned near the drive, which ejects the cartridge.
Although the above-mentioned devices provide many useful features, IBM Corporation's introduction of multi-disk optical cartridges creates a new problem. In packaging, the multi-disk optical cartridge format resembles the single-disk optical cartridge. To use the cartridge, it is inserted substantially into the drive. However, a grippable face portion of the cartridge remains outside the drive, advantageously permitting the user to remove the cartridge at certain times. For instance, the cartridge may be removed from a drive after one of its disks has been mounted in that drive. However, when a disk is transferred between the cartridge and a disk drive, the withdrawal of the cartridge may damage the disk drive. Therefore, the multi-disk cartridge must be locked in place at certain times.
For multi-disk cartridge applications, then, the existing disk drives are not satisfactory. The rigid diskette drive and single-disk optical cartridge both permit the user to withdraw the diskette at any time by pushing an eject button. The floppy drive permits the user to withdraw the diskette at any time by pivoting the latch and slidably withdrawing the diskette.
At first glance, some benefit appears to be available by studying systems related to compact disks ("CDs") used to play music. Like the multi-disk optical cartridge of the computer industry, music CDs are often dispensed in multiple disk magazines. The user first places multiple CDs in different trays of a CD magazine, and then the user loads the CD magazine into a CD player. Then, the CD player individually loads a CD, optically reads it, and generates an electrical signal representative of the digital music stored on the CD.
Like multi-disk cartridge drives in computers, CD players are potentially vulnerable to damage from premature removal of the CD magazine. In particular, a CD player may be damaged if the CD magazine is withdrawn while the CD player is inserting a CD into the CD magazine or removing a CD therefrom. Thus, engineers have designed CD players that enclose their CD magazines sufficiently to prevent users from gripping and removing the CD magazines. When the CD magazine is inserted sufficiently into the CD player, the CD player mechanically conveys the CD magazine deeply into the CD player, often so that the CD magazine's face is flush with the CD player's face. This prevents premature removal of the CD magazine, since the user simply cannot get a grip on the CD magazine. To remove the CD magazine, the user presses an "unload" button, causing the CD player to restore all CDs to the CD magazine and eject the CD magazine.
Although CD players may provide certain advantages for some applications, this art is unsatisfactory for use with the new multi-disk optical cartridges of the computer industry. First, as mentioned above, a CD player effectively locks-in a CD magazine by enveloping it so deeply that a user cannot grip the CD magazine. However, as discussed above, computer-readable multi-disk cartridges are constructed so that a grippable face of the cartridge protrudes from a drive when the cartridge is inserted into the drive. With this arrangement, the cartridge cannot be drawn into the drive, as a CD magazine would be drawn into a CD player. In fact, this would be undesirable since it may be advantageous to insert a multi-disk cartridge into a disk drive, load one disk from the cartridge into the disk drive, then permit a user or a library picker to remove the disk from the drive without disturbing the presently loaded disk. However, a multi-disk cartridge of this arrangement is susceptible to premature removal from the disk drive, presenting a problem that is not addressed by the CD art.
Accordingly, the state of the art is inadequate to solve the problems presented by the new multi-disk optical cartridge systems.